Noyau Linux et développement de drivers

Introducing the Linux kernel (architecture, compilation)
Introducing the kernel development APIkernel module API
char, network and block devices
kernel support for PCI, USB and platform device
Introducing the device tree
Debugging and profiling  kernel and drivers

A practical work is available for each item with a “star” (*).

Linux introduction

• Introducing the Linux project
• Licensing !
• Linux (UNIX) architecture (user/kernel space)
• Introducing “systemd”
• Using Linux kernel sourcesObtaining the source code
  Configuration
  Native (x86) and cross compilation (ARM) *
  

The kernel module API

• Writing a simple “Hello World” module *The “init” and “exit” functions
  Writing a Makefile *
  Loading and unloading module using “kmod”
  
• Module dependencies *
• Using module parameters *

The char driver API

• Module vs driver
• Drivers categories (char, block, network)
• Char driver syscalls (open, read, write, close, ioctl)
• Registering a char driver *
• Using kernel “classes” *
• Using the CDEV interface *
• Locking features (“spinlock” and “mutex”) *
• Managing hardwareMemory allocation *
  Interrupt handling *
  I/O ports and memory-mapped access *
  Memory mapping (the “mmap” system call) *
  DMA *
  
• Writing a generic PCI driver *
• Writing a simple USB driver (HID) *
• Using the platform device/driver API for embedded systemsIntroducing the device tree (with the QEMU/ARM platform)
  DT syntax and examples *
  Using “configfs” to load a DT overlay *
  

The network driver API

• Using Linux network
• Introducing network drivers
• The “net_device” and “net_device_ops” structures
• Socket buffer (SKB)
• Writing and testing the “faketh” dummy network driver *

The block driver API

• Block driver vs char driver
• The new “blk-mq” framework (Linux kernel 5.x)
• Writing a simple block driver (using ramdisk) *

Interacting with user space

• Device node approach limitation (USB but no hotplug !)
• Understanding “sysfs”
• Using “udev”  *
• “Netlink” sockets
• Writing and testing rules *
• modalias (device / driver association) *
• Using “udevadm”

Debugging drivers

• Using GDB in kernel space (QEMU/ARM)
• Debugging static kernel and module (.ko)
• Profiling kernel and drivers with Ftrace (debugfs) -> trace-cmd